Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!caesar.cs.montana.edu!milton!uw-beaver!sumax!quick!srg
From: srg@quick.COM (Spencer Garrett)
Newsgroups: comp.unix.questions
Subject: Re: #! troubles
Keywords: exec, kernel, environment
Message-ID: <7661@quick.COM>
Date: 17 Jan 90 04:43:45 GMT
References: <2047@uvaarpa.virginia.edu> <1990Jan15.215617.9659@i88.isc.com>
Organization: Quicksilver Engineering, Seattle
Lines: 15

In article <1990Jan15.215617.9659@i88.isc.com>, daveb@i88.isc.com (Dave Burton) writes:
> In article <2047@uvaarpa.virginia.edu> worley@compass.com writes:
> >> Assuming the kernel gets your $PATH (which it doesn't, but pretend) -
> >
> The kernel does not get _any_ environment variables. Sure, it passes an
> environment pointer to the exec'd process, but this does not imply the
> environment is scanned. That would be _very_ expensive.

Au contraire.  The environment strings are *copied* to the child process
in the same manner as the argv strings.  The kernel could easily scan
for a PATH variable.  The main argument against this is that it's the
sort of feeping creaturism for which Berkeley has been long and loudly
chastized, though given that #! interpretation got moved in I don't
see this as an inappropriate adjunct.  I think it got left out mostly
because coding this sort of thing at the kernel level is a mess.